If you've installed Snow Leopard then you've no doubt noticed the wonderful blue glow that encompasses the selected window when Exposé is activated. Many people have pointed out how "un-Apple" this style is when compared to the rest of the operating system. Fortunately, the style of Exposé is controlled in a similar manner to that of the Dock, which means that it can easily be customized. I've tried out several modifications people have made ranging anywhere from simply removing the color in the glow to a fancy transparent outline.

I liked the idea behind the transparent outline, but didn't really feel that the angle of the lighting was that balanced (white on one side, but not on the other). I decided to make my own customization such that there was still the transparent effect but the window was outlined symmetrically and didn't draw attention to the sides so much.

There currently aren't any nice installation programs for this modification like there are for the Dock, but it's really not too complicated. The outline is controlled by two different .png files, so changing the style is as simple as replacing them with different images.

These files are located at the following path:/System/Library/CoreServices/Dock.app

Once you have the Dock.app selected, right click and choose the "Show Package Contents" option.

Now navigate to:Contents/Resources

Locate the following two images, which control the outlines of normal windows and minimized windows:

expose-window-selection-big.pngexpose-window-selection-small.png

At this point I'd recommend backing up the originals either by copying them somewhere safe or duplicating them (select and press Command+D). I included the originals in the download just in case.

Now move the two custom images into the folder. You will be asked to authenticate the movement, so simply enter your password and confirm the replacements. If you get a weird error message, try deleting the two original files and then move the custom images into the folder.

Now that you've replaced the images, the Dock.app needs to be restarted so the new images are loaded. There are two ways of doing this 1) by logging out and back in or 2) opening the Terminal application, typing killall Dock, and pressing enter. This will quit the Dock application, allowing the images to be reloaded.

Fire up Exposé and you should see the new style when you hover over the windows! Of course, you can modify the images however you want, just make sure you keep the same filename, format, and size.